Mounting



N. E' LEE June 5, 1951 MOUNTING Filed July 7' 1945 FIG. 1.

Patented June 5, 1951 UNITED STATES PATENT orifice (Granted under the act of March 3, 1883, as amended April 30, 1928; 370 O. G. 757) 12 Claims.

The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

The present invention relates to improvements in m-ountings (Case 6) and more particularly to improvements in mounting means of the type used to sustain a load relative to a base, so as to prevent, or at least minimize, the transmission of vibrations, shocks and noises from said load to said base, and vice versa.

Some installations require mounts which will protect against a number of different kinds of impulses. For instance, in aircraft sensitive apparatus must be shielded from forced vibrations of the engines and associated parts, at various speeds, including that speed at which there are generated vibrations of the resonant frequency of the mounted equipment, and also from shocks occurring in rough air and when landing.

In marine installations, `provision must be made not only against vibrations set up by the engines, shafts and propellers, which operate at variable speeds, usually of lower frequencies than in aircraft, but also against deflections caused by pitching and rolling of the vessel.

In vehicular installations the problem is more complicated as the supports must provide protection against forced vibrations of the engines and associated parts, operating at variable speeds, including the natural vibrating frequencies, vibrations due to substantially uniform, minor irregularities of the road beds traversed by the vehicles, which usually have abrupt Wave-forms, and shocks due to holes and abnormal irregularities in the road surfaces. These conditions are greatly exaggerated in the case of military vehicles which often must cover terrain far rougher than that covered by other vehicles and which may also be subjected to ballistic impacts and concussions.

Vibration and shock mounts of the prior art, although used in tremendous quantities, have been found to be badly defective in performing their intended purposes.

Some mounts are capable of curtailing the transfer of vibrations of relatively high frequency, but are unsatisfactory because they allow vibrations at the resonant or natural frequency of the supported load to be so greatly amplified as to be seriously detrimental.

Some operate to attenuate deiiections in only one direction of movement, such as vertical, and are therefore unsuited to installations requiring attenuation in several directions.

Some are equipped with snubbers which come into play abruptly when the deflections reach a certain amplitude and, as a result, they set up violent counterforces and regularly recurrent shocks Which are often more destructive to sensitive apparatus than the vibrations and shocks which the mounts are intended to absorb.

Again, some mounts are so designed that, if the spring material (such as rubber) is injured, as by tearing, or there is a separation of a bond between the spring material and the metal, the mounted equipment may separate entirely from the base and be severely damaged.

Some supports, having hydraulic systems comprising a cylinder and a piston operating therein, have excellent vibration damping characteristics but are relatively large in size and are expensive to manufacture and maintain, and they also are subject to leakage of the hydraulic medium therefrom. In addition, they are generally good in only one direction and they require a spring system separate from the hydraulic system.

Some mounts put a tensile loading on the spring material, which results in greater drift and greater sensitivity to injury than other types of loading.

In some mounts, oscillations persist and add to later oscillations so as to amplify rather than reduce them.

It is intended by the present invention to provide shock and vibration supports which are not attended by defects of earlier mounts.

It is an object of the present invention to provide means of supporting equipment which will satisfactorily isolate and absorb vibrations and shocks of various frequencies.

It is also an object to provide a mount which may be stiff enough so as not to unduly amplify low frequency and resonant frequency oscillations, but still soft enough to attenuate high frequency oscillations and thrusts of great force, Without giving rise to countershocks.

It is another object to provide a mount which incorporates both a shock absorbing system and a spring system in a single unit.

It is still another object to provide supports wherein the action of the spring system facilitates the operation of the absorbing system.

It is a still further object to provide such mounts wherein natural rubber or a similar material may be used as the spring system and wherein deformations of said material are utilized to accelerate the functioning of the shock absorption system.

It is a further object to provide supporting means which will cushion displacements in different directions, such as vertical, horizontal and rotational.

Another object is to employ hydraulic damping in mounting devices which are so designed that they will not suffer from leakage of the hydraulic medium, which will be small in size relative to earlier hydraulic mounts, which will not incorporate solid, nonresilient parts moving against each other with resultant wear, and changes in operating characteristics and replacement of parts.

It is still another object to provide mounts in which the hydraulic medium is confined in eX- tensible chambers which provide the necessary volumetric capacity for the medium under different conditions of operation.

Still another object is to provide mounts having external dimensions which allow them to be substituted for presently manufactured mounts without necessitating structural changes in either the base or the load.

A still further object is to provide mounts designed to absorb and attenuate shocks in most directions to such a degree as to eliminate the need of snubbers and thereby avoid the violent countershocks frequently caused thereby.

It is still another object to provide mounts wherein metal to metal contacts are eliminated and hence the transfer of sound, as well as vibration and shock, is inhibited.

lt is also an object to provide a mount which, despite unusual vibrations and shocks, and wear and tear, will not allow the equipment sustained thereby to tear loose entirely from the base.

It is yet another object to provide a mounting wherein the resilient material is subjected to a corrective tension to minimize the possibility of drift due to repeated compression or flexure.

It is another object to eliminate tensile loading of the spring material and the disadvantages resulting therefrom.

Generally, a mounting embodying the present invention includes a spring element, of a resilient, flexible material (such as natural or synthetic rubber), which, when deflected in at least one direction, is initially relatively stiff and gets softer and finally gets stiff again at extreme amplitudes. Such a spring element is preferably tubular in shape, and is first put into compression and acts as a column, and then collapses and goes into exure. Such a spring element is relatively stiff under normal loads and will thus prevent undue amplification of the lower frequency vibrations (which are involved particularly in vehicular suspension), but under sharp surges gets progressively softer, so as to prevent the transmission of large force impulses to the equipment, and then gets progressively stiffer, so as to stop deflections within the amplitude limitations of the mounting without the need of abruptly acting snubbers. Each spring element is also tted with means to apply a slight longitudinal tension to it each time it is deformed so as to counteract the possibility of drift of the material. In the interior of the mount is a chamber lled with a suitable hydraulic medium, which is forced about within the chamber by deformations of the spring element described above.

A preferred embodiment, as illustrated in the drawings and as hereinafter described in more detail, comprises a load spool including two parallel load plates joined by a core; a base plate, having a large central opening, interposed between and parallel to said load plates; two generally tubular spring elements interposed respectively between the base plate and each of the load plates. Said spring elements are suitably secured to opposite sides respectively of the base plate and to the peripheral portions of webs of similar resilient material, The inner portions of said webs are secured to the load'spool. Each of said spring elements is preferably of the type described above. The interior of said mount forms a chamber lled with a suitable hydraulic medium, such as oil.

In the accompanying drawings, Figure 1 is a perspective View, partly cut away, of a preferred form of mounting embodying the present invention, shown in its normal, at rest, condition;

Figure 2 is an elevational View, to a reduced scale, of the mounting (with the fastening bolts removed) of Figure 1, partly broken away and vertically diametrically sectioned, showing the mounting when the base plate and associated parts are deflected upwardly a small amount and the upper spring element is acting as a column under compression;

Figure 3 is a View similar to Figure 2, the base plate and associated parts being shown deflected upwardly to their positions of nearly maximum amplitude;

Figure 4 is a fragmentary similar vertical cross sectional view, the base plate and associated parts being shown deflected laterally to the left;

Figure 5 is a fragmentary view similar to Figure 4, the base plate, etc., being shown deflected rctationally in a clockwise direction;

Figure 6 is a fragmentary vertical section of a modified form of the mounting of Figures 1 5, wherein each spring element is encircled by a hoop which bows it inwardly so as to modify the operating characteristics of the mount;

Figure 7 is a fragmentary vertical section of a second modied form, wherein each of the spring elements is preformed with an inward bow about its central portion, so that any vertical thrust causes direct exure.

Referring now particularly to Figures 1 through 5, the mounting there shown is made up of a base assembly II, the base plate I3, a load spool I5, and upper and lower spring assemblies ITU, I1L.

The base assembly II is made up of a vertically positioned, short, square tube I9, of heavy sheet metal, into each of the corners of which is securely fastened, as by welding, a vertically disposed, internally threaded, square, metal boss 2 I. The base plate I3 is a horizontally disposed square plate of heavy sheet metal, provided with a relatively large, centrally disposed, circular opening 23 and pierced by four small corner holes 2Q.

The load spool I5 includes a vertically disposed circular metal core 25, axially pierced by a circular hole 2 which is screw threaded at its middle portion. The upper and lower end portions 213D", ZSL of said core 25 are of lesser outside diameter than the central portion 30 thereof, so as to form the upper and lower rabbets ZBU, 29L. Secured to the opposite ends of said core 25, and normal thereto, are horizontally disposed, upper and lower load plates SIU, 3IL which are flat circular disks of heavy sheet metal, are centrally pierced by countersunk openings and are rigidly secured to the opposite ends of the core, as by swaging. The core 25 and the load plates 3IU, 3IL, integral therewith, form the load spool I5. The core 25 extends through the opening 23 in the base plate I3, the load plates 3IU, SIL being parallel to said base plate I3 and above and below it.

The lower spring assembly IlL is made up of a lower elastic member 39L, a lower auxiliary base plate 33L which is a duplicate of the base plate I3 mentioned above, a lower interior washer 35L and a lower exterior washer 3IL. The interior washer 35L is of a size to allow it to iit into the rabbet ZQL. The two washers 35L, 3IL and the auxiliary base plate 33L are coaxially disposed, the washers 35L, 3'IL being coplanar and spaced from and below said plate 33L. The lower elastic member 39L, of a suitable resilient flexible material (preferably a fairly stiff compound of natural or synthetic rubber), is secured (as by a rubber-to-metal bond) to the said lower washers 35L, 3'IL and the lower auxiliary base plate 33L.

Said elastic member SSL is generally cupshaped, being provided with a lower, horizontally disposed, flat, washer-like web 4IL and a lower, collapsible, tubular, spring element 43L. Said lower web 4IL is pierced by a central aperture of a size to make a snug fit about the central portion 3l) of the core 25. The lower spring element 43L is provided with an exterior circumferential channel ASL. The two lower washers 35L, 3'IL are ilush with the lower surface of the cup-shaped, elastic member 39L.

Said lower spring assembly IIL is interposed between the base plate I3 and the lower load plate 3IL, the base plate I3 and the lower auxiliary base plate 33L being superimposed in register and securely fastened to each other (as by seam-welding), and the lower interior washer 35L being held tightly in the rabbet ZBL by the lower load plate SlL. An upper spring assembly I'IU. which is a duplicate of the lower spring assembly ITL, but in an inverted position, is similarly interposed between the base plate I3 and the upper load plate 3IU.

Encircling the core 25 and extending between the upper and lower webs IIIU, ML, is a vertically disposed tubular sleeve 41, of rubber-like material. Thus, it will be seen that there is formed an interior annular hydraulic chamber 49 which is nlled with a suitable hydraulic medium (not shown), such as oil.

The base plate I3 and the upper and lower auxiliary base plates 33U, 331. are seam-welded together, as aforesaid, to form an integral member. which is secured to the upper end of the base assembly II by means of four, flat headed, countersunk, machine screws 5I, which are threaded into the upper ends of the bosses ZI. The opening 21 is provided with a bolt 53 and the lower end of each of the four internally threaded bosses 2| is provided with a bolt 55.

In the modication, shown in Figure 6, the mount is the same as that already described and illustrated in Figures l-5, except that, surrounding the spring elements 43U, 43L and disposed in the channels 45U, AEL respectively, are upper and lower hoops 5IU, 5'IL which are of a diameter to slightly bow the central portions of said spring elements inwardly, circumferential-ly, so that vertical thrusts on the mount cause said spring elements 43U, 4.3L to go into lexure directly or when subjected to thrusts of lesser force than would produce ilexure in the absence of the hoops 5'IU, 5'IL.

The modied form, illustrated in Figure 7, is also similar to the form first described, except that the spring elements 59U, 5.9L are preformed 6 with an inwardly extending circumferential bow, with the result that any vertical thrust recults directly in ilexure of said spring elements.

In describing the operati-on of the embodiment of the present invention illustrated in Figures 1-5, it will be assumed that the mount is being used to sustain a radio set in a motor vehicle. When so installed, the mounting is secured to the chassis of the motor vehicle (not shown) by means of the four bolts 55 and the radio set (not shown) is secured to the mounting by means of the bolt 53.

When so' installed, vibrations and shocks of various frequencies and directions are imparted to the chassis of the motor vehicle, as a result of operation of the motor thereof, road bed irregularities, etc. As most vibrations and shocks and particularly those of greater force and amplitude will p-robably be found to occur mainly in a vertical direction, the mount should be installed with its axis disposed vertically, as shown in the drawings, as its vibration and shock attenuating properties are greatest in that direction. 'I'he base assembly I I, the base plate I3 and the upper and lower auxiliary base plates 33U, 33L will oscillate vertically with the chassis of the motor vehicle. Vertical thrusts of relatively little force will cause the spring elements 43U, 43L to alternately undergo vertical compression as a column (such compressionof the upper spring element 43U being illustrated in Figure 2). Under vertical thrusts of greater force, the said spring elements 43U, 43L will be caused alternately to collapse and bend inwardly into ilexul'e (as shown in Figure 3, Where the upper element 43U is shown collapsed).

It will be noted that, under no condition of operation, are the spring elements 43U, 43L subjected to excessive vertical tension. This is due to the fact that the said spring elements 43U, 43L are not connected directly to the end plates 3IU, 3IL, but only by way of the webs lIIU, 4IL. Thus, when the base plate I3 is deflected upwardly, the lower end of the lower spring element 3L and the lower exterior washer 31L,

integral therewith, move upwardly withY said plate I3, so as to move away from the lower load plate 3 IL. The outer periphery of the lower web lIIL is thereby pulled upward while its inner periphery is held down by virtue of the fact that the lower interior washer 35U is locked against the lower end plate 3I U. On the other hand, the web, when so deformed, does exert a slight downward tensional pull on the lower end of the lower spring element 43L, thereby helping to neutralize any drift of the resilient material, which might otherwise result from the repeated compressive and flexure strains to which it is subjected.

` Any horizontal oscillations of the motor vehicle chassis cause similar horizontal oscillations of the base assembly II, the base plate I3 and the auxiliary base plates 33U, 33L,' thereby causing the spring elements 43U, 43L to be put A into shear (as indicated in Figure 4) thereby attenuatinc,r horizontal components of vibrations and shocks.

Should there be any twisting or rocking movements imparted to the base plate I3, the mount described has sufficient rotational compliance to attenuate them (as shown in Figure 5). Any other movements imparted to the base plate I3 will merely be a combination of the movements already described.

It will be noted that, in all of the deections described, the shape and size of the hydraulic chamber 49 are being changed constantly thus requiring that the hydraulic medium contained therein be pushed around within said chamber, thereby resulting in an absorption of energy. This is particularly true in the event that a highly viscous medium, such as very heavy oil, is used.

It will be understood that, although the amplitude of the mount just described is limited toward the ends of vertical strokes, the mount gets progressively stiffer as it approaches a maximum deflection and thus stops movements gently, without any abrupt jolts, as occur in mounts utilizing bumpers.

The modiiied forms, shown in Figures 6 and 7, indicate how the load-deflection curve of such a mount may be varied for particular installations. In the first of said modifications (Figure 6) hoops STU, SlL are placed respectively around the spring elements 43U, ASL so as to entirely eliminate any column action at all. The hoops 5'.'U, lL may be of metal, or even of a resilient material, such as natural or synthetic rubber. Any vertical thrust on the mount causes the spring elements 43H. QSL to go directly into exure and collapse. If it is merely desired to change the load-deflection curve of a mount (as shown in Figures 1-5) so as to change the point Where collapse will occur, this may also be accomplished by hoops 51U, ETL which bow the spring elements 43U', 43L inwardly but very little. It is notable that by the artice of supplying several hoops 51U, 51L with a particular mount, its load-deection characteristics may be so varied and its load range may be so increased as to reduce the I number of different mounts which must otherwise be manufactured for various installations. Thus, a mount may be fabricated with relatively heavy and stiff spring elements 43U, 43T.. so as to take relatively heavy loads but the same mount may be softened up to take lighter loads in several ranges by providing it with several sets of hoops E'IU, ETL.

The spring elements EQU, 59L of the second modied form of mounting (Figure '7) are so shaped that they will go directly into iiexure upon being subjected to any vertical thrust, due to the fact that the preformed inward bow of said spring elements makes it impossible for them to act as columns under compression at all.

The steady energy absorption by the hydraulic system, of the mounts described above, combined with the increasing recovery force stored up in the spring systems as the amplitude of deflection increases, results in a time lag in the deflection, thereby keeping the amplitude of deflection within the predetermined limits of a particular mount. Thus, by a steadily increasing storage and absorption of energy, the vibrations and shocks are attenuated without the use of snubbers, which may act with an injurious abruptness.

An important feature of the present invention is that axial deflections of small amplitude cause relatively large changes in the shape of the hydraulic chamber 49. This relatively large change in shape is particularly advantageous Where a hydraulic medium of low viscosity is used as it results in a more rapid movement of the medium about said chamber and, hence, a greater absorption of energy. Low viscosity liquids may sometimes be preferred because they may be more satisfactory over greater temperature ranges. It will be understood that the hydraulic medium may be either gaseous, or liquid, or a combination of both. In some installations such combination would be helpful so as to allow volumetric changes Within the hydraulic chamber 49 Without undue deforming strain on the material of the elastic members SBU, 391.'. A compressible medium also helps to compensate for pressure changes due to temperature variations.

It should be noted that the present mount is so constructed that it is capable of depending for attenuation almost entirely on the elastic characteristics of the resilient material, or it can depend both upon that and the energy absorption of the hydraulic system. The spring action of the resilient material in itself is capable of accepting considerable energy. rI'his phenomenon is discussed below, without reference to the hydraulic action, in connection with the explanation of the energy absorption due to the loaddeilection characteristics of a mount. It will be understood, of course, that the hydraulic effect in the present mount Will be greatest the more viscous the medium. If it is not desirable to accentuate the hydraulic effect, air would be a desirable hydraulic medium in the chamber 49. However, if considerable hydraulic effect, compared to the spring action attenuation is desirable, the relative spring action can be lessened by the modications shown in Figures 6 and 7, or by using a more viscous medium.

To appreciate the superiority of mounts embodying the present invention, some study of load-deflection curves is profitable. Many commercial mounts today have a substantially linear load-deflection curve; that is, deection and load increase at about a constant ratio except that, toward the end of the curve, the load increases more rapidly than the deflection. Thus, a loaddeflection curve for such a mount is a fairly straight slanting line which swings upward steeply toward the end.

Mounts embodying the present invention, on the other hand, as already explained, are relatively stii at rst, then get softer, and nally get stiff again. Thus, a load-deflection curve for such mounts is initially quite steep and then proceeds at a lesser slope and finally swings upward again to the end of the curve.

It should be understood that a shock mount which has the best load-deection curve is one which, for a given displacement and energy absorption will transmit the smallest forces.

One of the members to which a shock mount is fastened such as the chassis of a motor vehicle in the example mentioned above has a certain kinetic energy due to its movement. This energy must be accepted ideally by the shock mount. The energy is translated in the shock mount to the potential energy involved in straining the resilient material. The potential or strain energy is the work done in deforming the mount and it is equal to the area under the portion of the loaddeflection curve traversed. The greater the thrust to which a mount is subjected and. hence, the greater the attendant kinetic energy, the larger the area under the curve.

Thus, it is seen that a mount is most satisfactory when its deflection curve is such that, for a given deflection, the area under the curve is at a maximum. It is obvious that a load-deflection curve, which is initially steep and then proceeds at a lesser slope (as in the present mount), will provide more area under it and, hence, more energy absorption than a deflection curve which is relatively linear (as is typical of present commercial shock mount practice, as mentioned above).

For thrusts having relatively large energy, it

will be understood that, to absorb said energy, a

relatively large area under the load-deflection curve is necessary. As the load-deflection curve of the present mount provides such area throughout the beginning of the curve, the deflection of the mount need not be as great as for commercial mounts having a relatively linear curve and, hence, the force transmitted by the present mount is less than that transmitted by such commercial mounts.

Although the embodiments shown in the drawings have particular geometries, it will be understood that various changes in geometry may be made within the spirit of the invention. Such changes in geometry, and changes in relative sizes of elements, and other modifications may be made to suit the present mounting to different compounds of natural or synthetic rubber, to different hydraulic mediums and to different loading values.

Although not shown in the illustrated embodiments, it would be helpful to incorporate means for injecting the hydraulic medium into the chamber 49 after the mountings are assembled.

Although a'particular mount will obviously be designed with certain loads, vibrations and .shocks in mind, it is conceivable that in use a mount may be subjected to unanticipated conditions or it may be used beyond the intended useful life span of its resilient material. this occur the resilient material may rupture or one of the bonds between the elastic members 39U, 39L and the auxiliary base plates 33U, 33L and the washers 35U, SSL may let go. Nevertheless, tne load will not separate from the base and fly into space as the base plate I3 and the auxiliary base plates 33U, 33L are imprisoned upon the load spool I5.

It will be understood that the mounts described will also operate with the base assembly ll secured to a load and the load spool l5 secured to a base.

While there have been described what at present are considered preferred embodiments of the present invention, it will be obvious to those skilled in the art that various changes and modications may be made therein without departing from the invention and it is, therefore, aimed in the appended claims to cover such changes and modifications as fall within the true spirit and scope of the invention.

What is claimed is: 1

1. A mount to sustain a load relative to a base, comprising a base plate provided with a central opening; a load spool, including a core extending substantially axially through said opening, and two load plates secured substantially normally to said core, and on opposite sides respectively of said base plate; two elastic members interposed between said base plate and said load plates respectively, each of said elastic members including a substantially tubular spring element adapted to undergo longitudinal compression in response to slight thrusts and to collapse into flexure under shocks of greater force, said spring elements respectively being secured at one end to opposite sides of said base plate; two webs secured respectively to the other ends of said spring elements, the inner portions of said webs being secured to the load spool proximate to the two load plates respectively.

2. A mounting as set forth in claim 1, wherein there is incorporated a hydraulic chamber bounded at least in part by said spring elements Should and said webs; and a hydraulic medium within said hydraulic chamber.

3. A mounting to sustain a load relative to a base comprising a base plate and two auxiliary base plates disposed respectively on opposite sides of said base plate and secured thereto to form an integral member, all of said plates being pierced by openings in register with one another; a load spool, including a central core and two load plates secured normally thereto, said core extending axially through the openings aforesaid, and the load plates being disposed parallel to the said auxiliary base plates and respectively spaced therefrom; two tubular spring elements interposed respectively between the two load plates and the two auxiliary base plates, each such spring element being of resilient iiexible material and being bounded by a Substantially cylindrical inner surface and a substantially concave circumferential outer surface, so that it will undergo compression under relatively slight axial thrusts and will collapse inwardly into flexure under greater axial thrusts, a first end of each of said spring elements being bonded to one of said auxiliary base plates; and two washer-like webs of resilient material, the inner portions of which are secured to the load spool, and the outer peripheral portions of which are secured respectively to the second ends of the spring elements.

4. A mounting as set forth in claim 3, wherein a stiff washer is secured to the outer peripheral portion of each of the webs, and each stii washer and spring element is movable relative to the adjacent load plate during operation.

5. A spring assembly for a mounting, comprising a plateya substantially cup-shaped elastic member of resilient exible material, said elastic member including a substantially tubular spring element and a substantially ilat web positioned across one end of said tubular spring element the outer portion of said web being joined to the said end of the spring element; a stii washer embedded in the said exible material at the junetion of the spring element and the web; a second stiff washer embedded in the web at its inner portion; the other end of the spring element being secured to the plate; the second washer and the inner portion of the web being free to move axially relative to all of the other parts described above, the material of the web allowing such movement.

6. A mounting to support a load relative to a base, comprising in combination a base plate having an opening therethrough; means to secure said base plate to the base; a load spool including a core and two spaced load plates secured substantially normally thereto, the core extending through the said opening in the base plate, and the base plate being positioned intermediate and spaced from said load plates; means to secure the load spool to a load; two substantially cup-shaped elastic members of resilient flexible material interposed respectively between the two load plates and the base plate, each such cup-shaped member including a tubular spring element, the outer central surface of which is provided with a circumferential ccncavity, and a web disposed substantially normally to said tubular spring element and secured to one end thereof, said web being provided with a central opening encircling the core; a stiff washer secured to the end of said spring element which is joined to the web means to secure the inner marginal edge of the web to the load spool; a sleeve of resilient material encircling the core il intermediate the webs; the two cup-like elastic members facing each other and forming therebetween a completely enclosed extensible annular hydraulic chamber; and a hydraulic medium within said chamber.

'7. A mounting as set forth in claim 6, wherein a hoop encircles each spring element and is adapted to bow it inwardly,

8. Means to modify the operational characteristi'cs of a vibration mounting of a type which includes a substantially tubular spring element, comprising a hoop surrounding said spring element and adapted to bow it inwardly.

9. A spring member for a shock mount comprising a substantially tubular spring element of resilient flexible material, which element undergoes longitudinal compression during operation, and means to subject said element to a slight longitudinal tension after such compression, said tensioning means including a web secured to one end of said tubular spring element and a stiff substantially washer-like member secured to said spring element proximate to its juncture with said web to maintain the conguration of said spring element during operation.

10. A mount to sustain a load relative to a base, comp-rising a base plate provided with a central opening; a load spool, including a core extending substantially axially through said opening, and two load plates secured substantially normally to said core, and on opposite sides respectively of said base plate; two elastic members interposed between said base plate and said load plates respectively, each of said elastic members including a substantially tubular spring element, said spring elements respectively being secured at one end to opposite sides of said base plate; two webs secured respectively to the other ends of said spring elements, the inner portions of said webs being secured to the load spool proximate to the two load plates respectively.

l1. A mounting to sustain a loa-d relative to a base comprising a base plate and two auxiliary base plates disposed respectively on opposite sides of said base plate and secured thereto to form an integral member, all of said plates being pierced by openings in register with one another; a load spool, including a central core and two load plates secured normally thereto, said core extending axially through the openings aforesaid, and the load plates being disposed parallel to the said auxiliary base plates and respectively spaced therefrom; two tubular spring elements interposed respectively between the two load plates and the two auxiliary base plates, each such spring element being of resilient exible material, a rst end of each of said spring elements being bonded to one of said auxiliary base plates; and two washer-like webs of resilient material, the inner portions of which are secured to the load spool, and the outer peripheral portions of which are secured respectively to the second ends of the spring elements.

12. A mounting to support a load relative to a base, comprising in combination a base plate having an opening therethrough; means to secure said base plate to the base; a load spool including a core and two spaced load plates secured substantially normally thereto, the core extending through the said opening in the base plate, and the base plate being positioned intermediate and spaced from said load plates; means to secure the load spool to a load; two substantially cup-shaped elastic members of resilient flexible material interposed respectively between the two load plates and the base plate, each such cup-shaped member including a tubular spring element, and a web disposed substantially normally to said tubular spring element and secured to one end thereof, said web being provided with a central opening encircling the core; a stili washer secured to the end of said spring element which is joined to the web; means to secure the inner marginal edge of the web to the load spool; a sleeve of resilient material encircling the core intermediate the webs; the two cup-like elastic members facing each other and forming therebetween a completely enclosed extensible annular hydraulic chamber; and a hydraulic medium within said chamber.

NORMAN E. LEE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS France Oct. 10, 1939 

